I've been having a problem starting my 87 GT for the last few months. It's been a very reliable daily driver with 80k miles. For a while it just took a bit longer to start in the morning but progressed until recently it would no longer start at all on the cold mornings. It would generally start just fine later in the afternoon so I suspect the cold start system.

(I've not had to use the car for a while since my stolen 88GT was recovered and put back into service. Yes, that one. So my troubleshooting took a back seat for a while)

Anyway, It seemed like a cold start system issue to me. A week or so ago I finally replaced the cold start switch connector. It felt a bit off to me and I was hoping for a quick resolution. Unfortunately, that did not solve the problem.

This morning I decided to check that there was actually power getting to the switch. I removed both fuel injector fuses and disconnected the connector at the cold start switch. Using my test light I connected the ground lead to a chassis ground strap and checked both contacts very quickly (within 3 seconds) while the engine was cranking.

To my surprise the test light glowed on both contacts. I assumed only one would have power. This can't be right, can it?

How cold is it where you live? My cold start injector system was deleted by the previous owner, and my car has started just fine in 25 degrees fahrenheit, albeit a little slow. Unless you start it in weather a lot colder, Id suspect something else as the main problem.

[This message has been edited by Xenoblast (edited 03-07-2022).]

quote Originally posted by Xenoblast: How cold is it where you live? My cold start injector system was deleted by the previous owner, and my car has started just fine in 25 degrees fahrenheit, albeit a little slow. Unless you start it in weather a lot colder, Id suspect something else as the main problem.

It can be between 35 to 45 degrees some mornings. I know that is not severe compared to other parts of the country, but the problem seems to be related to temp so that is where I started. Completely open to other suggestions.

Still trying to find out if I am supposed to be getting voltage on BOTH pins to the cold start switch. ( I am checking during the first few seconds of cranking phase with the injector fuses removed )

This is from the 87 Factory Service Manual.

You will see voltage at both pins 1 and 2. If I am reading the wiring diagram correctly, the cold start switch is a relay. Pin 2 activates the relay that connects pin 1. Both should show power during cranking.

[This message has been edited by Doug85GT (edited 03-07-2022).]

That was extremely helpful!

Thanks guys!